China
Africa
Explore chapters and articles related to this topic
Biocomposites and Nanocomposites
Published in Amit Sachdeva, Pramod Kumar Singh, Hee Woo Rhee, Composite Materials, 2021
C. H. Lee, S. H. Lee, F. N. M. Padzil, Z. M. A. Ainun, M. N. F. Norrrahim, K. L. Chin
Polysaccharides are biological polymers composed of monosaccharide units with glycosidic linkages, known as long chains of carbohydrate molecules. The chain can be linear or branched, which may influence its reaction to water. The functions of polysaccharides in living organisms are structure-related like cellulose and chitin or storage-related like starch and glycogen. A polysaccharide that contains all the same type of monosaccharide repeating units is called homopolysaccharide or homoglycan but if more than one type of monosaccharide is present then it is named heteropolysaccharide or heteroglycan. The chemical formulae of monosaccharide and polysaccharide are (CH2O)n and Cx(H2O)y, respectively. Glucose, fructose, and glyceraldehyde are examples of monosaccharides.
Chemical Structures of Cellulose, Hemicelluloses, and Lignin
Published in David N.-S. Hon, Chemical Modification of Lignocellulosic Materials, 2017
Gyosuke Meshitsuka, Akira Isogai
Higher plants including wood, some algaes, tunicates (sea animal), and some bacteria produce cellulose, which is a homopolysaccharide consisting of (3-D-glucopyranose residues linked by glucoside bond at their Cl and C4 hydroxyl groups (Fig. 1). Cellulose has three hydroxyl groups per anhydroglucose residue and thus some functional groups are introducible into cellulose by esterification, etherification, deoxyhalogenation, and other reactions. However, such chemical modifications of cellulosic materials are sometimes difficult to achieve freely at the hydroxyl groups. Solid state structures of cellulose, i.e., intra- and intermolecular hydrogen bonds, crystallinity, crystal size, crystal structures, interactions with water, molecular mass and molecular mass distributions, presence of lignin or hemicelluloses, shape and size of cellulosic materials and others, greatly influence reactivity of the cellulosic materials, efficiency of the reactions, and finally properties of the chemically modified cellulosic materials.
Seaweeds
Published in Parimelazhagan Thangaraj, Phytomedicine, 2020
L. Stanley Abraham, Vasantharaja Raguraman, R. Thirugnanasambandam, K. M. Smitha, D. Inbakandan, P. Premasudha
The polysaccharides in their sulfated form were abundantly found in the cell wall of seaweeds (Pereira 2018). The sulfated polysaccharides and their derivatives are the complex polymers that differ by their occurrence, structure, and function. They can be extracted from all the classes of macro algae, such as green (Chlorophyceae), red (Rhodophyceae), and brown (Phaeophyceae). The Chlorophyceae such as Monostroma and Ulva sp. result in the production of sulfated polysaccharides viz. ulvan and rhamnan (Liu et al. 2018; Tziveleka et al. 2018; Wang et al. 2018). The Rhodophyceae species of Gracilaria, Hypnea, Laurencia, and Gigartina contribute to the production of galactans and carrageenan (De Almeida et al. 2011). Fucoidans and fucans are brown seaweed’s sulfated polysaccharides, which are abundant in several species such as Sargassum, Padina, Ascophyllum, Nizamuddina, Dictyopteris, Dictyota, and Kjellmaniella (Li et al. 2008). Polysaccharides are biopolymers comprising of same or different monomers to form the essential components for the living system. They have a wide diversity among their composition of monomers, such as direct, interrupted repeat, alternating repeat, block copolymer, branched, and complex repeat. The analysis made on these structures may lead to a better understanding of their function. The polysaccharide is composed of individual sugar units linked with glycosidic linkages, and functional groups. Based on monomeric constituents, it can be divided into a homopolysaccharide, acquired from the same type of sugar residues, and heteropolysaccharide, made from the linkage of different monomers as tabulated in Table 3. The higher and diverse structure of various kinds of polysaccharides tends to possess certain unique biological activities. Specificity augments among these polysaccharides due to their interchain interactions (Eric 2005; Harding et al. 2017). Moreover, the sulfated polysaccharides possess high therapeutic potential as compared to other forms of polysaccharides.
Variations of organic matters and bacterial community during hyperthermophilic biodrying process of sewage sludge
Published in Drying Technology, 2022
Kai Wu, Rencheng Zhu, Peiyi Li, Yukai Zheng, Zhanbo Hu
The hemicellulose content of HB was stable in the first 3 days, and accelerated degradation in the thermophilic phase. During the entire biodrying, the contents of hemicellulose in HB and CB decreased from 139.2 g kg−1 and 141.9 g kg−1 to 96.2 g kg−1 and 103.5 g kg−1, respectively. The hemicellulose consumption rate of HB was a little faster than that of CB in the thermophilic phase, and the two consumption rates were basically the same in the cooling phase. In the processes of HB and CB, cellulose contents decreased from 154.5 g kg−1 and 154.8 g kg−1 to 138.4 g kg−1 and 145.5 g kg−1, respectively. The cellulose mainly degraded in the thermophilic and cooling phase of HB and CB. Ma et al also found that cellulose degraded rapidly in the thermophilic phase of composting.[27] The contents of lignin increased slightly in HB and CB processes, which might be due to the concentration effect caused by the rapid degradations of other organic matters in the matrixes. In HB, the degradations of cellulose and lignin were much lower than hemicellulose, because their structures are quite different from hemicellulose. Cellulose is a homopolysaccharide consisted of D-glucosyl units linked by β-1,4-glycosidic bonds. Lignin is consisted of three alcohol monomers. Hemicellulose is a kind of heteropolysaccharide which contains different sugar units.[21] Therefore, hemicellulose is more easily hydrolyzed by enzymes than cellulose and lignin.
Carboxymethyl cellulase production optimization from Glutamicibacter arilaitensis strain ALA4 and its application in lignocellulosic waste biomass saccharification
Published in Preparative Biochemistry and Biotechnology, 2018
Chirom Aarti, Ameer Khusro, Paul Agastian
Lignocellulose is a pivotal source of renewable energy consisting of cellulose, which is in fact structurally, and compositionally complex hemicellulose and recalcitrant lignin.[1] Cellulose is the most copious renewable natural homopolysaccharide in the biosphere.[2] The cellulolytic enzymes synergistically act on cellulosic biomass and hydrolyze them into fermentable sugars in order to produce bioethanol. Cellulase is a multi-enzyme system comprised of endo-1,4-β-D-glucanase (EC 3.2.1.4), exo-1,4-β-D-glucanase (EC 3.2.1.91), and β-glucosidase (EC 3.2.1.21). The endoglucanase (carboxymethyl cellulase) randomly attacks β-1,4 bonds in cellulose, producing glucan chains of different lengths, whereas exoglucanase acts on the ends of the cellulose chain and releases β-cellobiose as the end product. β-glucosidase catalyzes the hydrolysis of glycosidic bonds to non-reducing residues in β-D-glucosides and oligosaccharides, thereby releasing glucose.[3] Despite the substantial necessity of cellulase in bioresource technologies, they are also enormously utilized in diversiform bioprocess industries viz. food, wine, brewery, pulp and paper, textile, pharmaceutical, detergent, livestock, and agriculture.[4]